src/engine/InstancePool.h

#ifndef INSTANCEPOOL_H
#define INSTANCEPOOL_H

#include <map>
#include <list>
#include <stack>
#include <boost/shared_ptr.hpp>
#include "TemplateTable.h"
#include "VariableTableTemplate.h"
#include "VariableTableInstance.h"
#include "Variable.h"
#include "util/Error.h"

namespace green
{
  class InstancePool
  {
  public:
    virtual ~InstancePool() {}
    
    ID AddInstance(VariableTableInstancePtr inst)
    {
                        CHECK_SHARED(inst);
      inst->SetID(this->_getUnusedID());
      mIDMap[inst->GetID()] = inst;
      return inst->GetID();
    }

    bool HasInstance(ID id) const
    {
      _idMap::const_iterator i = mIDMap.find(id);
      return(i != mIDMap.end());
    }

    VariableTableInstancePtr GetInstance(ID id) const
    {
      _idMap::const_iterator i = mIDMap.find(id);
      if(i == mIDMap.end())
        THROW_ERROR("that id does not exist in this pool");
      return i->second;
    }

    void RemoveInstance(ID id)
    {
      _idMap::iterator i = mIDMap.find(id);
                        ERROR_ASSERT(i != mIDMap.end(), "that id does not exist in this pool");
      mReusedIDs.push(i->second->GetID());
      mIDMap.erase(id);
    }

  protected:
    ID _getUnusedID()
    {
      if(mReusedIDs.empty())
        return mIDMap.size();
      else {
        ID ret = mReusedIDs.top();
        mReusedIDs.pop();
        return ret;
      }
    }

    typedef std::map<ID, VariableTableInstancePtr>
            _idMap;
                                
    _idMap mIDMap;

    std::stack<ID> mReusedIDs;
  };
        typedef boost::shared_ptr<InstancePool> InstancePoolPtr;
        #define INSTANCE_POOL_CAST(x) boost::dynamic_pointer_cast<InstancePool>(x)
}

#endif

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